package com.killer.filter;

import org.springframework.cloud.gateway.filter.GatewayFilterChain;
import org.springframework.cloud.gateway.filter.GlobalFilter;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.http.HttpStatus;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.stereotype.Component;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Mono;

import java.util.ArrayList;
import java.util.List;

/**
 * @author ：Killer
 * @date ：Created in 20-12-30 下午4:40
 * @description：${description}
 * @modified By：
 * @version: version
 */
@Component
public class BlackListFilter implements GlobalFilter{

    // 模拟黑名单(实际可以去数据库或者redis中查询)
    private static List<String> blackList = new ArrayList<>();
    static {
        // 模拟本机地址
        blackList.add("0:0:0:0:0:0:0:1");
    }
    /**
     * 过滤器核心方法
     * @param exchange 封装了request和response对象的上下文
     * @param chain 网关过滤器链(包含全局过滤器和单路由过滤器)
     * @return
     */
    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        // 思路:获取客户端ip,判断是否在黑名单中,在的话就拒绝访问,不在的话就放行
            // 从上下文中取出request和response对象
        ServerHttpRequest request = exchange.getRequest();
        ServerHttpResponse response = exchange.getResponse();
        // 从request对象中获取客户端ip
        String clientIp = request.getRemoteAddress().getHostString();
        // 拿着clientIp去黑名单中查询,存在的话就决绝访问
        if(blackList.contains(clientIp)) {
        // 决绝访问,返回
            response.setStatusCode(HttpStatus.UNAUTHORIZED); // 状态码
            String data = "Request be denied!";
            DataBuffer wrap =
                    response.bufferFactory().wrap(data.getBytes());
            return response.writeWith(Mono.just(wrap));
        }
        // 合法请求,放行,执行后续的过滤器
        return chain.filter(exchange);
    }
}
